Shelf stable tea concentrates are highly desirable and have several applications. These include: the ability to supply a natural tea concentrate for use in Ready-to-Drink tea and Fountain tea products; as a tea concentrate product for retail sale; and as a preferred method of transporting tea solids. The advantages of a tea concentrate over a powder or a dilute tea extract are that better tea character is obtained. In addition, less energy is employed than for a powder and less weight and volume are needed for shipping a concentrate than for a dilute extract.
In the prior art, tea concentrates were considered to be physically unstable, which prevented their use in many tea products. However, it is believed that under certain conditions tea products made from tea concentrates have better quality (e.g., flavor, freshness, etc.) than powders and are more economical than tea powder or dilute tea extract. Therefore, it is highly desirable to have a shelf stable tea concentrate.
The addition of a selected level of high methoxy citrus pectin stabilizes tea products having about 0.1% tea solids and prevents haze and precipitation. This is disclosed in U.S. Pat. No. 5,529,796. However, the same approach to stabilize tea concentrates up to about 40% solids was not successful.
U.S. Pat. No. 4,748,033 disclosed the use of edible gums (xanthan gum, cellulose gums, locust bean gum, sugar gum and mixtures) to prevent flake formation during cyclic freezing and thawing, and to enhance cold water solubility. The solids level for the tea concentrate specified in the patent was 0.4 to 8% (w/w) and the use level of xanthan gum was 5-12% weight of gum to weight of tea solids.
U.S. Pat. No. 4,051,267 to Jongeling disclosed the use of carrageenans for suspending and stabilizing tannins in a tea extract which is transported in a frozen or chilled condition for use in vending machines. However, Jongeling found that the viscosity of the tea extract using xantham gum was so high that the accuracy of dosing in the dispensing machine was impaired.
The use of individual gums or mixtures of gum with selected tea extracts has been disclosed. However, the current invention is very different from the teachings of the prior art. The prior art dealt with much lower levels of tea solids, i.e. 0.4-8%. Further, the prior art did not stabilize tea concentrates containing 20-70% solids. Additionally, the prior art required low temperatures (refrigerated or frozen) to maintain the flavor, clarity, stability and shelf life of the products. Tea concentrates prepared by the current invention in contrast to the art are stable at ambient temperatures. The use level of xanthan in this invention on a tea solids basis is very low 0.5-2.5%. Lastly, xanthan gum is the most effective out of 14 gums/stabilizers screened including carrageenans and pectins.
Accordingly an object of the invention is to prepare enzymatically extracted tea concentrates at high concentrations which may be stored at ambient temperature for at least six months with good quality. It is believed that this is the first time that tea solids at such high concentrations have been stabilized for extended periods at ambient temperatures.
Yet another object is to provide stable tea concentrates at relatively low pH values as low as about 2.5.